RFC 333 (rfc333) - Page 2 of 26

Proposed experiment with a Message Switching Protocol

RFC 333          MESSAGE SWITCHING PROTOCOL EXPERIMENT          May 1972


SOME BACKGROUND

   Over the past several weeks there has been considerable informal
   discussion about the possibility of implementing, on an experimental
   basis, in several of the ARPA Network Host Computers, NCPs which
   follow a protocol based on the concept of message switching rather
   than the concept of line switching (see the parenthetical sentence in
   the first paragraph of page 6 of NIC document 8246, Host/Host
   Protocol for the ARPA Network).  Party to this discussion have been
   Bob Bressler (MIT/Dynamic Modeling) Steve Crocker (ARPA), Will
   Crowther (BBN/IMP), Tom Knight (MIT/AI), Alex McKenzie (BBN/IMP), Bob
   Metcalfe (MIT/Dynamic Modeling), Dan Murphy (BBN/TENEX), Jon Postel
   (UCLA/NMC), and Dave Walden (BBN/IMP).

   Several interesting points and conclusions have been made during this
   discussion:

      1. Bressler has implemented a message switched interprocess
         communication system for the Dynamic Modeling PDP-10 and has
         extended it so it could be used for interprocess communication
         between processes in the Dynamic Modeling PDP-10 and the AI
         PDP-10.  He reports that it is something like an order of
         magnitude smaller than his NCP.

      2. Murphy has noted that a Host/Host protocol based on message
         switching could be implemented experimentally and run in
         parallel with the real Host/Host protocol using some of the
         links set aside for experimentation.  Further, Murphy has noted
         that if this experimental message switching protocol were
         implemented in TENEX, a number of (TENEX) sites could easily
         participate in the experiment.

      3. It is the consensus of the discussants that Bressler should
         take a crack at specifying a message switching protocol* and
         that if this specification looked relatively easy to implement,
         a serious attempt should be made by Murphy and Bressler to find
         the resources to implement the experimental protocol on the two
         BBN TENEX and the MIT Dynamic Modeling and AI machines.

      4. MSP was chosen as the acronym for Message Switching Protocol,
         and links 192-195 were reserved for use in an MSP experiment.



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   *This note fulfills any obligation Bressler may have incurred to
   produce an MSP specification.




Bressler, et al.            Experimentation